The present disclosure relates to the field of tomosynthesis and to a method and system for processing tomosynthesis imaging data for obtaining enhanced projection images.
X-ray imaging systems have become a valuable tool in medical applications such as for the diagnosis of many diseases. As standard screening for breast cancer mammography 2-dimensional (2D) x-ray images are taken across the entire breast tissue. These known 2D mammograms are limited by tissue superimposition. That is to say, lesions may be masked by the tissue above or underneath, or normal structures may mimic a lesion. In order to minimize limitations of standard 2D-mammography caused by tissue superimposition, digital breast tomosynthesis using digital receptors has been developed.
The tomosynthesis systems employ at least one x-ray tube, which is moved in an arc above a stationary detector. In digital breast tomosynthesis (DBT) the volume information of an object of interest can be derived from a series of images, known as projection images or projections, which are taken at various angles by means of one or more x-ray sources. Objects of different heights in a breast display differently in the different projections. From the 2D projection images 3D volumes can be generated for review. The generated 3D volume portions offer advantages to overcome the limitations associated with tissue superimposition.
During the adaption period of the tomosynthesis technology, the provision of the known 2D mammography is still desired by medical professional or radiologist, who want to use existing expertise gained from reviewing 2D mammograms. Furthermore, archived 2D-mammograms can be better compared with images obtained with the same technology than with images of a new modality as tomosynthesis.
To address the need for 2D mammograms besides the provision of the relatively recent tomosynthesis images, it is known to perform a combo acquisition of images. That is to say both the known 2D mammography and digital breast tomosynthesis are acquired for the same object of interest. However, since the average dose from tomosynthesis imaging is approximately the same as the known mammogram 2D imaging, the radiation exposure is roughly doubled. Thus, there is the need, to generate or acquire the information of known 2D mammograms without performing two examinations, in order to reduce the dose.
One problem to be addressed is that images acquired during tomosynthesis through digital receptors may be contaminated by a variety of noise sources. By noise we refer to stochastic variations as opposed to deterministic distortions such as lack of focus. One drawback is that a single tomosynthesis projection image at a given orientation or x-ray source position is very noisy because the dose per projection is not enough to be compared to a known 2D mammogram acquisition. Accordingly, there is a need to improve image quality comprising noise management in order to offer a tomosynthesis 2D image that looks like a known full-dose 2D mammogram in order to enable high quality diagnostic.
Further, there is the need to facilitate lesion identification by a health professional by providing further reviewing modalities, wherein not only one 2D image but also one or more 3D images are provided. This addresses the need for possible navigation and smooth transition from 2D to 3D images.